Various methods and apparatus are known for producing holes in durable material. Among these, rotary drills and hammer drills employ drill bits that include cutting and/or breaking surfaces arranged to remove a portion of the substrate material as the drill bit is advanced. In certain drill bits, one or more helical features, such as helical grooves or channels, serve to withdraw the removed substrate material away from the cutting and/or breaking surfaces. In some cases, the helical features extend over much of the length of the drill bit so that removed material is extracted out of the substrate material altogether.